1. Field of the Invention
This invention relates generally to electrical terminal apparatus and, more particularly, to connector-protector apparatus for use on a modular main distribution frame system in a telephone central office.
2. Description of the Prior Art
The main distribution frame system in a telephone centrl office is the focal point of many work activities and the system serves many diverse purposes, such as: interconnection juncture for joining central office equipment with outside plant facilities; access point for testing into or out of the central office; and protection provisioning interface. Thus, in a functional sense, the frame system provides for connection, testing and protection. Physically, in conventional frame systems, separate apparatus serve each function.
Modular main frame systems have decreased craftsperson activity and reduced frame administration time by supplanting earlier frame systems which typically required a two-person team to run jumpers and necessitated cumbersome frame administration procedures.
In a modular frame system, outside plant pairs first appear on protector apparatus and terminate on connector apparatus; also, central office equipment terminates on connecting blocks similar to the connector apparatus. Oftentimes, the connector and protector apparatus are located on separate, spaced-apart frames which facilitate administration procedures and craftsperson activity but impose a concomitant increase in floor space requirements. Electrical interconnection of an outside plant wire to a central office equipment terminal comprises a series path including a protector device and a so-called jumper connection. The protection device is inserted into a protector panel which forms a component of the protector apparatus; the device generally provides series as well as shunt protection against excessive voltage and current appearing on the series path. Access to outside plant facilities for protected testing is effected from a separate, stand-alone test field appearance which bridges the series interconnection path. Unprotected testing into either the outside plant or central office may be effected at the protector panel whenever the protector device is removed.
U.S. Pat. No. 4,057,692, issued to DeBortoli et al on Nov. 8, 1977, is representative of prior art central office terminal apparatus in which three separate fields, namely, connector, protector and test, are readily identified. DeBortoli et al disclose the typical arrangement wherein an outside plant stub cable is directly wire-wrapped to the outside plant side of protector panel sockets which seat the protector device. Bridging jumpers connect test points in the test field to the outside plant stub cable appearances on the sockets. The connector field serves as an interconnection point for outside plant and central office equipment leads. Backplane wiring furnishes the jumper connections that link the connector field with sockets on the protector panel associated with central office side of the protector socket. Protector devices are guided and held in place with wall-type dividers. The walls have apertures which mate with corresponding projections on the protector to provide full-seated or so-called detent positioning.
Another example of modular terminal apparatus is disclosed in U.S. Pat. No. 4,012,096, issued to DeLuca et al on Mar. 15, 1977. In this design the three standard fields are also discernible. In addition, both the ouside plant stub cable and the outside plant cross-connect terminal field leads are wire-wrapped to pin couplets that appear side-by-side on the connector face. Interconnection is effected with shorting plugs having metal receptacles which mate with the pin couplets. It is alluded to, but not disclosed, that the plugs may be adapted to provide protection. Separate test field appearances of the cable pairs are provided by bridging to the connector appearances of the pairs.
While terminal apparatus of these types do suffice for the intended purposes of connection, protection and testing, they also exhibit shortcomings. One severe shortcoming is that the stand-alone appearance of the test field results in oversized apparatus with the concomitant excessive use of frame area. Related shortcomings are the additional production and material costs associated with providing a separate test field. A further disadvantage lies in the labor-intensive installation procedures, particularly the time-consuming effort devoted to wire-wrapping sockets or pins.